I was single for many years. Intimacy cannot be underrated. But, just as easily as you can find "love" you can be distracted from it if your core being is not being attended to. One of the most important things I have found when it comes to relationships is Abraham Maslow's theory of the hierarchy of needs. Let's say that a SO symbolizes sexual need. Once, you satisfy that need, others arise. The need for intimacy can be left in the dust if say someone isn't reading enough novels, writing enough books, playing and writing enough music. What you are good at and what you enjoy doing is your purpose. If anyone or anything gets in the way of that then no matter how good someone else feels, that value is going to diminish. We cannot help but oscillate among our needs. I have always had crushes that turned into relationships that didn't last long because they became my primary focus. And similarly, someone you love, who gets in your way doing the things you love or are good at, they eventually become less and less important. And sure, as soon as you loose them due to your disinterest, you want them back, because intimacy rears its ugly head as the unsatisfied need.